Processing method device and system to produce a focused image signal from an unfocused image

ABSTRACT

A method and apparatus are disclosed for forming an image signal by receiving a flux of photons at a convex photodetector such as a hemispherical photodetector. The convex photodetector includes a plurality of photosensors. Each photosensor has a different orientation with respect to a propagation vector of the flux of photons. The photosensors generate a respective plurality of intensity signals. Each of the intensity signals is related to the respective orientation of the photosensor that generates it. The intensity signals are received by a signal processor, such as a digital signal processor, which uses the intensity signals to compute an image signal related to the intensity signals and thereby produce a focused output image.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. provisional patentapplication Ser. No. 60/617,139, filed Oct. 8, 2004, the disclosure ofwhich is herewith incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to imaging systems and more particularlyto digital imaging systems.

BACKGROUND OF THE INVENTION

Conventional optical photographic and video cameras, telescopes andmicroscopes are used to display and/or record images. Such systems relyon reflective and refractive optical lenses. The refractive opticallenses serve to focus light within the systems. Typically, the lensesare made of glass or plastic, and exhibit fundamental characteristicssubstantially unchanged since the time of Galileo. Refractive opticallenses range in size from microscopic dimensions to meters across.

A refractive lens focuses an image by directing to a particular point ona focal plane photons originating at a corresponding point in an imageplane. For purposes of discussion, the general lens problem may besimplified to the problem of a lens focused “at infinity.”

Generally, incoherent light diverges from a light source. At largedistances from the light source, however, this divergence becomesnegligible. Consequently, light arriving at a receiving device from asource at a large distance from the receiving device arrives alongsubstantially parallel rays. The distance from the image plane at whichlight rays appear substantially parallel depends on the characteristicsof the system sensing the light. For a typical photographic camerafocusing beyond approximately 40 feet is equivalent to focusing atinfinity.

Unfocused light uniformly illuminates a plane disposed in the path ofthe arriving light rays. This uniform illumination carries lessinformation content than a focused image, in which variation of lightintensity across the focal plane corresponds to variation of lightintensity at the image plane.

One simple apparatus for forming a focused image is a pinhole aperturedisposed in a substantially opaque barrier where the opaque barrier isdisposed in spaced relation to a reflective or translucent screen. Apinhole camera includes an opaque barrier having an aperture therein.The pinhole camera provides a focused image on a reflective, translucentor optically sensitive screen that is disposed in spaced relation to thebarrier. The focused image is related to the distribution of lightarriving from a distant image plane.

The barrier blocks all of the light arriving at the barrier from aparticular light source except for the portion of that light arrivingincident to the aperture. Light arriving at the aperture passes throughthe aperture and impinges on the screen. Light arriving from differentlight sources arrives at different solid angles with respect to thebarrier, and accordingly illuminates correspondingly different regionsof the screen.

A pinhole camera uses available light inefficiently. The image includesonly light arriving directly at the aperture. Other light arriving atthe barrier is absorbed by, or reflected from, the barrier and is thusunavailable for image formation. Furthermore, the resolution of theimage on the screen is limited by aperture size. A small aperture formsa higher-resolution image than a large aperture. A smaller aperture,however, allows a smaller proportion of the light arriving from aparticular source to pass through to the screen, while a correspondinglylarger portion of the incident light is reflected or absorbed by thebarrier.

A refractive lens uses incident light much more efficiently to form animage. Typically, light arriving along parallel rays from a distantsource is collected across an entire surface of a refractive lens.Wherever the light impinges on the lens, it is redirected towards apoint on a focal plane. In an ideal case, image resolution on the orderof the wavelength of the incident light can be achieved, and theefficiency of the system is high, since most of the light incident onthe surface of the lens is transferred to the focal plane, rather thanbeing reflected or absorbed.

While refractive lens systems provide relatively high efficiency andresolution, they have significant disadvantages. The geometry of arefractive lens is constrained by the index of refraction of thematerial or materials of which the lens is formed, and by the refractioneffects desired. Consequently, the shape and volume of a refractive lenssystem is constrained within certain parameters. In particular, thedepth of the lens system may be non-negligible in the overall design ofan optical system. To some extent lens system thickness may be reducedby applying fresnel lenses, however use of a fresnel system impliesother design constraints. In addition, optical materials havingdesirable refractive characteristics may be relatively dense, resultingin correspondingly heavy focusing systems.

Recent years have witnessed significant advances in electronic imagingtechnology. In particular, the technology of charge coupled devices andCMOS photosensors has developed rapidly. CMOS devices are now availablewith significant integrated processing capability such that photosensorarrays and digital signal processing devices are mutually disposed on acommon substrate. Consequently, electronic photosensors are now employedin a wide variety of imaging applications and apparatus.

With digital electronic photosensors has come improved methods of imagestorage. Images acquired by digital cameras are readily adapted to bestored and manipulated in digital format. Such manipulation includespostprocessing of images acquired by conventional image acquisitionsystems to extract information present, but not readily visible, in theoriginal image. Various algorithms and mathematical transform techniqueshave been applied to the processing of images acquired throughrefractive lens systems. Nevertheless there remains a need for compactand light-weight image acquisition systems capable of acquiring imageswith reduced mechanical complexity. In view of these and otherlimitations, there exists an opportunity to advance the state of theart.

BRIEF DESCRIPTION OF THE INVENTION

It is desirable to have a focusing system adapted to receive light andproduce a focused image or a signal corresponding to a focused imagewithout the use of refractive or reflective optics. In addition, it isdesirable to have a focusing system capable of operating at highefficiency with respect to detecting incident light. Further, it isdesirable to have a focusing system that is readily manufacturable andrelatively insensitive to manufacturing process variation. Moreover, itis desirable to have a focusing system that is adaptable to changingenvironmental influences, and readily reconfigurable for optimalresponse to particular application parameters. Further, it is desirableto have a focusing system that is light in weight and able to provide ahigh-resolution image with a reduced form factor. In a further aspect itis desirable to have a focusing system adapted to provide as an output,a signal readily stored or transmitted to a remote location.

A digital imaging system according to the invention includes a lightgathering device and a computational infrastructure. The light gatheringdevice must acquire angular and intensity information concerningincident light and the computational infrastructure must transform theacquired information into usable images. Accordingly, a digital imagingsystem according to the invention produces a focused image bycomputationally processing signals received from a photosensor device.In this way, the digital imaging system is able to create focused imageswithout employing a refractive lens. By eliminating the need forrefractive lenses, optical systems such as cameras may be produced whichare smaller and lighter than comparable systems using conventionallenses.

A digital imaging system according to the invention is scalable, and isamenable to preparation by micro-fabrication techniques. In view of thefollowing disclosure, one of skill of the art would readily understandthat digital lenses may be prepared in various sizes from microscopicscale upward. A sensor array of decimeter scale for a digital imagingsystem would be highly portable and may be capable of gathering lightmore efficiently than a conventional system of comparable size andweight. As a result, lensless digital imaging systems are capable ofhigh-speed image acquisition, low-light image acquisition, andhigh-resolution image acquisition.

The present invention relates to a digital system adapted to receive afirst input signal and produce a second output signal corresponding to afocused representation of the first input signal. In one aspect, thepresent invention relates to a digital system adapted to receive anoptical input signal and produce a visual output signal corresponding toa focused representation of the optical input signal. In a furtheraspect, the present invention relates to a computing system adapted toreceive a plurality of electromagnetic waves and responsively produce animage corresponding to a spatial pattern of the electromagnetic waves.

These and other advantages and features of the invention will be morereadily understood in relation to the following detailed description ofthe invention, which is provided in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows, in cross-section, a portion of a digital imaging systemwith a collimated photosensor array;

FIG. 2 shows, in cross-section, a portion of a digital imaging systemwith an un-collimated photosensor array;

FIG. 3 shows a plurality of photosensors having different respectiveorientations according to one embodiment of the invention;

FIG. 4 shows an idealized response curve of a digital imaging system;

FIG. 5 shows, in block diagram form, a digital imaging system accordingto one embodiment of the invention;

FIG. 6 shows a digital imaging system according to another embodiment ofthe invention;

FIGS. 7 a and 7 b show respective top and sectional views of a portionof a digital imaging system, including a plurality of photosensorsdisposed in a fresnel pattern;

FIG. 8 shows a portion of a digital imaging system including anarrangement of photosensors according to one embodiment of theinvention;

FIG. 9 shows a portion of a digital imaging system including anellipsoid photosensor array;

FIG. 10 shows, in block diagram form, a digital imaging system combinedwith conventional refractive lenses according to one embodiment of theinvention;

FIG. 11 shows a digital imaging system including a scanning photosensordevice; and

FIGS. 12 a-12 f show an image having large depth of field according toone embodiment of the invention.

FIG. 13 shows, in flowchart form, a method of forming a focused imageaccording to one aspect of the invention.

FIG. 14 shows, in additional detail, a method of forming a focused imageaccording to one aspect of the invention.

FIG. 15 shows, in flowchart form, a method of manufacturing and imagingsystem according to one embodiment of the invention.

DETAILED DESCRIPTION

The present invention will be described as set forth in the exemplaryembodiments illustrated in FIGS. 1-15. Other embodiments may be utilizedand structural or functional changes may be made without departing fromthe spirit or scope of the present invention. Like items are referred toby like reference numerals.

In a first aspect, the present invention relates to a digital imagingsystem adapted to receive an optical input signal from one or moreremote active or passive light sources and produce an image outputsignal corresponding to the optical signal. The invention may include adisplay device adapted to display a visual image according to the imageoutput signal, and may further include a storage device adapted to storethe image output signal for display at another time. In one aspect, theinvention includes a sensing system for sensing light intensity arrivingfrom a plurality of directions with respect to the sensing system.According to one embodiment of the invention, the sensing systemincludes a plurality of photosensors oriented in a respective pluralityof directions in relation to the sensing system.

Referring to FIG. 1 one sees, in cross-section, a hemispherical portionof a digital imaging system according to one embodiment of theinvention. As shown in FIG. 1, the digital imaging system includes aphotosensor array 100. The photosensor array 100 has a plurality ofphotosensors exemplified by photosensors 102, 103, 104.

In the photosensor array 100, photosensor 102 has a light-receivingsurface 112 disposed in substantially normal relation to an orientationvector 106. Photosensor 104 is disposed in substantially normal relationto an orientation vector 108. The orientation vectors coincide with arespective plurality of lines that intersect at a common point 110,which point 110 defines a center of a hemisphere.

The light-receiving surface 112 of each photosensor is oriented toreceive light from a region 114 outwardly of the light-receiving surface112, as taken with respect to the center point 110. Each light-receivingsurface 112 is disposed in a substantially tangent relation to thehemisphere such that the light-receiving surfaces 112, taken together,are approximately coincident with a portion of the surface of thehemisphere. Therefore, according to one embodiment of the invention, thecombined light-receiving surfaces 112 of a plurality of photosensors,including photosensors 102-104 and others, form a piecewiseapproximation to a hemispherical surface.

According to the FIG. 1 embodiment, the digital imaging system includesa collimator 116. The collimator 116 includes an outer surface 118 andan inner surface 120. The collimator 116 also includes a plurality ofbore surfaces 122 disposed between the outer surface 118 and the innersurface 120 and defines a respective plurality of collimation passages124. According to one embodiment of the invention, the bore surfaces 122each include a substantially circular cylindrical surface. According toone aspect of the invention, the bore surfaces 122 are adapted to absorba substantial portion of any incident radiation including opticalfrequency electromagnetic radiation that impinges on the bore surface122. According to a further aspect of the invention, the bore surfaces122 are optimized to absorb electromagnetic radiation of a particularrange of wavelengths.

The collimation passages 124 are sized and oriented to allow light rays126 received from a particular solid angle with respect a referenceplane 128 containing the center point 110 to impinge upon thelight-receiving surface 112 of the corresponding photosensor 103. Lightrays received from outside the particular solid angle do not arrive atthe light-receiving surface 112, but impinge on, and are absorbed by,the bore surfaces 122 or the outer surface 118 of the collimator.Consequently, a photosensor signal is generated by the photosensor 103that is related to an intensity of light arriving at the photosensorarray 100 from light sources within a particular solid angle. Bycombining a plurality of such photosensor signals, the digital imagingsystem forms an output image signal corresponding to light arriving froman image plane.

As in the case of the pinhole camera, the amount of light received atany particular photosensor 103 of the FIG. 1 embodiment is limited bythe size of the aperture formed by the corresponding collimation passage124. Light arriving at a particular solid angle that does not passthrough the collimation passage 124 is unavailable for imaging. Asresolution of the FIG. 1 embodiment is increased, the proportion ofincident light available for use by each photosensor is decreasedcorrespondingly.

FIG. 2 shows a further embodiment of the invention including aphotosensor array 140. As shown, photosensor array 140 includes aplurality of photosensors A-R having a respective plurality oflight-receiving surfaces disposed to form a piecewise approximation of ahemispherical surface. Light rays 142 arriving from light source Y at aparticular solid angle Ω with respect to a reference plane 128 isreceived by more than one of the photosensors A-R. Since more of thelight arriving at solid angle Ω is collected by the photosensors, theefficiency of photosensor array 140 is higher than that of acorrespondingly sized photosensor array 100.

Formation of an image output signal requires both intensity and angularinformation regarding the light collected. In the case of thephotosensor array 100 (as in FIG. 1), angular information is acquired byvirtue of the collimation channels 124. In the case of the photosensorarray 140 (as in FIG. 2) angular information is extracted based on therelative light intensity detected by the plurality of photosensors A-R.Light arriving at a particular solid angle Ω, is substantially normal tothe light-receiving surface 112 of photosensor L. The light-receivingsurfaces 112 of other photosensors are positioned at respective angleswith respect to the incident light rays.

It should be noted that, while FIG. 2 shows a convex hemispherical arrayof photosensors, one of skill in the art would understand that a concavephotosensor array could also be used. Nor is the invention limited toarrays of hemispherical form. A wide variety of alternative shapes couldbe employed to good effect.

Referring now to FIG. 3, the geometric arrangement of exemplaryphotosensors D, G and L is considered in further detail. Each ofphotosensors D, G and L have equal area, and are equal in a lateraldimension d0. As noted above, light arriving at solid angle Ω issubstantially normal to the light-receiving surface 112 of photosensorL. As a result, photosensor L has an effective dimension d1 that issubstantially equal to dimension d0.

Photosensor G is disposed at a first non-normal angle with respect tothe incoming rays of light. Consequently, although photosensor G has,like photosensor L a dimension d0, it presents to the incoming rays oflight an effective dimension d2 that is smaller than d1. Consequently,for a given intensity of light source, a responsive signal produced byphotosensor G is smaller than the corresponding signal produced byphotosensor L.

Photosensor D is disposed at a second angle farther from normal, withrespect to the incident light rays, than either photosensor G orphotosensor L. Accordingly, photosensor D have a correspondingly smallereffective dimension d3 and generates a correspondingly smaller outputsignal in response to light arriving from light source Y.

FIG. 4 shows a curve that graphically represents output signal valuesproduced by photosensors A-R of photosensor array 140 in response tolight received from a light source Y. The curve of FIG. 4 has beensmoothed for simplicity of presentation. As is evident from the figure,a signal of maximum value is produced by photosensor L, while the otherphotosensors of photosensor array 140 produce signals of less than themaximum value according to their respective geometric orientations.

FIG. 5 shows an image acquisition system 150 according to one aspect ofthe invention. The image acquisition system 150 includes a photosensorarray 140 coupled to an analog to digital converter 154. The analog todigital converter 154 is, in turn, coupled to a computer processor 160.The computer processor 160 may be coupled to a digital memory device 164and/or a display terminal 170.

As shown in FIG. 5, photosensor array 140 receives light 142, 144 from aplurality of light sources (e.g., Y, Z) disposed in an image plane atinfinity. A plurality of light sensors A-R of the photosensor array 140produce a corresponding plurality of analog electronic signals 152. Theanalog electronic signals 152 are converted to a corresponding pluralityof digital signals 156 by an analog to digital converter 154. Theplurality of digital signals 156, taken together, form an intermediateimage signal 158 that may be represented as a first plurality ofnumerical values in a mathematical matrix. The intermediate image signal158 is received into a computer processor 160 (for example, a digitalsignal processor). The computer processor 160 operates on the firstplurality of numerical values of the mathematical matrix to produce asecond plurality of numerical values. The second plurality of numericalvalues may be received as a digital electronic signal 162 from thecomputer processor 160 at a digital memory 164 for short or long-termstorage of the second plurality of numerical values. The digitalelectronic signal 162 may also be received at a display circuit 166adapted to produce a display signal 168. The display signal 168 isreceived from the display circuit 166 at a display terminal 170, wherebyan image 172 corresponding to the light received from the light sourcesY, Z in the image plane is displayed by the display terminal 170.

An image is formed by inverting the response of the photosensors tolight incident from various angles. This can be achieved in thecontinuous case by the analytical solution of a Fredholm integralequation of the first kind, or in the discrete case by inverting amatrix containing values representing the response of the photosensors.In order to have a reasonable solution to the discrete problem, thenumber of sensors in the photosensor array must be comparable to thenumber of pixels desired in the image plane.

The spherical harmonics satisfy equation 1, as shown below.

∇² Y _(l) ^(m)(θ,φ)=−l(l+1)Y _(l) ^(m)(θ,φ)  I

As would be understood by one of skill of the art:

(∇²+2)cos θ=0  II

(∇²+2)0=0  III

Therefore:

(∇²+2)max(cos(θ),0)=0  IV

is true everywhere except at

$\theta = {\frac{\pi}{2}.}$

More specifically:

(∇²+2)cos θ=δ(θ)  V

The intensity operator transforms as a scalar under rotations, so by theWigner-Eckhart theorem, it preserves irreducible representations ofSO(3) and is a multiple of the identity in each representation. Thecoefficient can be determined by considering the action of the operatoron a point light source and combining with the previous result about theLaplacian.

$\begin{matrix}{{\int{{Y_{l}^{0}( {\theta,\varphi} )}( {\frac{1}{2\pi}{\delta (\theta)}} ){\Omega}}} = 1} & {VI} \\{{\int{{Y_{l}^{0}( {\theta,\varphi} )}{\delta ( {\theta - \frac{\pi}{2}} )}}} = {( {2\pi} )2^{- 1}{\cos ( {\pi \; {l/2}} )}( \frac{l}{l\; 2} )}} & {VII}\end{matrix}$

Therefore, the coefficient for l≠1 is:

$\begin{matrix}{( \frac{2\pi}{{l( {l + 1} )} - 2} )2^{- 1}{\cos ( {\pi \; {n/2}} )}( \frac{n}{n/2} )} & {VIII}\end{matrix}$

The l=1 coefficient is

$\frac{2\pi}{3}.$

Note that for l>1 odd, the coefficient is zero.

In light of the foregoing, one can solve for image intensity in the caseof a hemispherical sensor array. Note that in relation to the following,“E” designates the even part and “O” designates the odd part. Supposethe intensity function on the entire sphere is I(9, 0). Since thesources lie in θ<π/2, I and its first derivatives are zero at θ=π.

I(θ,φ)=E(θ,φ)=O(θ,φ)  IX

O(0)=I(0)−E(0)

=I(0)−E(π)

=I(0)−I(π)+O(π)

=I(0)−O(0)  X

Therefore:

O(0)=2I(0)  XI

Similarly, the fact that the derivative of I is zero at π requires:

dO(0)=2dI(0)  XII

The value of O at zero determines the m_(z)=0 component, thex-derivative determines the m_(x)=0 component, and the y-derivativedetermines the m_(y)=0 component. E can then be found from the relationE=I−O. The even component of the source can be determined as describedin section 1. The source pattern is twice the even component in theupper hemisphere and zero in the lower hemisphere.

Various processing errors tend to degrade the quality of the imageproduced by the digital imaging system of the invention. Image qualitymay be improved by compensating for numerical error in the design ofprocessing algorithms. According to one aspect of the invention,numerical processing algorithms performed by the computer processorinclude techniques to avoid round-off error. Also, as would beunderstood by one of skill in the art, error correction techniques maybe applied to the data received by the computer processor from theanalog to digital converter. Other sources of system noise includephoton statistical error. In addition, efforts to enhance the speed ofcomputation by approximation may result in systemic errors. Accordinglyerror correction and avoidance methods are employed as one aspect of theinvention.

According to one embodiment of the invention, the digital imaging systemcaptures one megabyte of data to populate a one million squared poorlyconditioned matrix. The poorly conditioned matrix is inverted and theresulting inverse matrix is stored. To produce an image the storedmatrix is multiplied by a million entry vector. In principle themultiplication requires 10̂12 arithmetic operations.

FIG. 6 shows a digital imaging system 180 according to a furtherembodiment of the invention. As shown, the digital imaging system 180includes a photosensor array 200 with a plurality photosensors 102, 103,104, etc. The photosensor have respective light-receiving surfaces 112disposed in an approximately spherical configuration. In one embodiment,the light-receiving surfaces 112 of the individual photosensors aresubstantially planar. According to one embodiment, the photosensor array200 is supported or suspended at a first end 206 of a supporting member208. The supporting member 208 is configured to obscure a minimum numberof light-receiving surfaces 112. According to one aspect of theinvention, a communication channel within the supporting member 208allows signals produced by the plurality of photosensors 102, 103, 104,etc. to be received by a processing system 210 coupled to a second end214 of the supporting member 208.

As shown in FIG. 6, light rays 220 from a sufficiently remote lightsource arrive in parallel at the light-receiving surfaces 112 of thephotosensor array 200. By virtue of the substantially spherical shape ofthe photosensor array 200, approximately one-half 222 of the array isilluminated by the incoming light. The other half 224 of the photosensorarray 200 remains in darkness. The photosensors 102, 103, 104, etc.receive different intensities of the incoming light 220 depending ontheir location in the photosensor array 200. The light-receiving surfacemost nearly normal to the incoming light rays produces a strongestoutput signal, while the light-receiving surface least nearly normal tothe incoming light rays produces a weakest output signal. The respectivesignals from all of the photosensors 102, 103, 104, etc. are processedin the manner described above (with respect to photosensor array 140) toproduce an output image signal.

FIG. 7 a shows a top view of a circular photosensor array 300 accordingto a further embodiment of the invention. In FIG. 7 a, thelight-receiving surfaces 112 of the photosensor array 300 are disposedin a fresnel pattern, rather than in the hemispherical pattern employedfor photosensor array 140.

As shown in FIG. 7 b, a thickness value h of the photosensor arraydevice 300 is less than a corresponding thickness of photosensor array140. However, photosensors may be disposed within the fresnelphotosensor array 300 having respective geometrical orientationssubstantially equivalent to the orientations of correspondingphotosensors of the hemispherical photosensor array 140.

FIG. 8 shows a further embodiment of the invention including aphotosensor array 400. The array 400 includes photosensors 402, 403, 404which are placed at various angles with respect to an image plane.Unlike the fresnel photosensor array 300, which exhibits circularsymmetry, photosensors 402, 403, 404 of a particular angle may be placedat any location that is convenient from a manufacturing or applicationperspective. According to one embodiment, the photosensors may be formedon a silicon substrate. Each photosensor, 402, 403, 404 has alight-receiving surface 412. The light receiving surfaces 412 need notbe smooth on a scale comparable to the wavelength of incident light.Instead, the light receiving surfaces may include a respective pluralityof steps 420 formed in, for example, a silicon material 422.

In one embodiment, the various angles of the photosensors 402, 403, 404increase according to a linear sequence. For example, successivephotoreceptors may be at angles of 0 degrees, 10 degrees, 20 degrees, 30degrees, etc. In another embodiment, a respective vector originating ata respective center point of each light receiving surface of eachphotosensor may be directed to an integer location on an arbitrary axis.

FIG. 9 shows a further aspect of the invention according to which thegeometrical configuration of the photosensor array may be optimizedaccording to a subject of the image. Accordingly, in one embodiment ofthe invention as shown in FIG. 9, the light-receiving surfaces of thephotosensor array may be arranged in a substantially ellipsoidarrangement. Such an ellipsoid photosensor array may allow optimalimaging of a generally ellipsoid photographic subject such as a humanface. One of skill in the art would understand that a wide variety ofsymmetrical and asymmetrical photosensor arrays may be preparedaccording to the requirements of a particular photographic subject.

FIG. 10 shows a further aspect of the invention, in which a digitalimaging system 150 may be applied in combination with conventionalrefractive and/or reflective optics to form a novel optical system 480.Included in the embodiment of FIG. 10 are a lens system 482 and an imageacquisition system 484. A lens system 482 may include one or moreconventional refractive lenses and/or reflective planar, convex, orconcave mirrors. The image acquisition system 484 may include aplurality of photosensor disposed in a respective plurality oforientations with respect to light received from a remote source throughthe lens system 482.

FIG. 11 shows a further embodiment of the invention including a scanningphotosensor device 500. The illustrated embodiment includes a pluralityof exemplary photosensors 102, 103, 104 with a respective plurality oflight-receiving surfaces 112. The light receiving surfaces are disposedin an arcuate arrangement and coupled to a shaft 502 at a first end 504thereof. A rotary actuator 506 is coupled to a second end 508 of theshaft 502. The rotary actuator is adapted to rotate the shaft 502 in themanner indicated by arrow 510, whereby the light-receiving surfaces 112described a substantially spherical surface centered about shaft 502.According to one aspect of the invention, during rotation of the shaft,data is repeatedly acquired from each of the photosensors 102, 103, 104,etc. whereby the acquired data is substantially similar to that whichwould be acquired from a corresponding spherical photosensor array.

As would be understood by one of skill in the art, alternative scanningmotions could readily be blended to address particular applicationrequirements. For example, the shaft 502 could be made to move in astepped fashion. The shaft could also be made to execute less than afull rotation. In addition, oscillatory motion of the shaft could beeffected to allow oversampling by the photosensors 102, 103, 104, etc.

In light of the foregoing, one of skill in the art would understand thatother scanning motions are also possible. For example, a singlephotosensor can be moved through a two-dimensional Cartesian or polarscanning pattern to acquire image information. In another example, alinear array of photosensor elements could be moved in linear fashion toaddress a two-dimensional set of sensor locations. Multiple lineararrays could also be concurrently or serially transported through alinear motion to allow oversampling, and a wide variety of specializedmotions, of constant or varying velocity, could be arranged to addressparticular light reception applications.

According to a further aspect of the invention, a digital imaging systemmay be used to provide artificially increased depth of field byintegrating a plurality of images acquired at differing focal lengths.FIGS. 12 a-12 f shows the preparation of an exemplary image formed byintegrating a plurality of images taken at a respective plurality offocal planes. In FIGS. 12 a-12 f, a portion of an insect is shown undermagnification. FIG. 12 a shows an uppermost portion of the insectportion in clear focus, the balance of the image is unfocused. FIGS. 12b-12 e shows successive regions of the insect portion in clear focus. Ineach case, the areas of the image field outside of the focal plane areunfocused. FIG. 12 f shows an image created by computationallyintegrating the focal plane images of FIGS. 12 a-12 e into a singleimage. According to one embodiment of the invention, the data setrequired for the preparation of the integrated image 12 f may be readilyacquired and stored in digital form prior to data processing of the datato produce the integrated image.

According to another aspect of the invention, as shown in FIG. 13, theinvention includes a method 600 of producing a focused image thatincludes several steps. One step 602 of the method includes receiving aflux of photons at one or more photosensor devices. Another step 604 ofthe method includes producing a plurality of electronic signals at thephotosensor devices corresponding to the received photon flux.

Additional steps of the method include receiving the electronic signalsfrom the photosensor devices at respective analog to digital converterdevices 606 and producing digital optical or electronic signals relatedto the electronic signals 608. Further steps of the method includereceiving the digital signals into a computer processor 610 andprocessing the digital signals 612 with the computer processor.

Further steps of the method 600 include receiving the output imagesignal at a digital memory device 614; storing a representation of theoutput image signal within the digital memory device 616; receiving theoutput image signal at a display device 618; outputting a visualrepresentation of the output image signal from the display device 620;and allowing a user to optically perceive the visual representation ofthe output image signal 622.

As shown in FIG. 14, the steps of processing the digital signals 612with the computer processor includes error-correcting the digitalsignals to produce corrected digital signals 630, 637; using thecorrected digital signals to populate a matrix represented in a memoryof the computer processor 632; mathematically inverting the matrixrepresented in the memory of the computer processor to produce aninverted matrix in the memory of the computer processor 634; multiplyingthe inverted matrix by a vector to produce a product matrix in thememory of the computer processor 636; and outputting a plurality ofvalues from the product matrix in the form of an output image signal638.

Although the exemplary embodiments discussed above include imagingsystems for visible wavelength radiation, one of skill in the art wouldunderstand that the invention may be readily adapted to receiveradiation of a wide range of wavelengths including gamma radiation,X-radiation, ultraviolet radiation, infrared radiation, microwaveradiation and radiofrequency radiation. In addition, the photosensorarrays may be readily adapted to acquire information related to imagecolor.

FIG. 15 shows a process 700 for manufacturing a photodetector deviceaccording to one aspect of the invention. As shown in FIG. 15, theprocess includes providing an appropriate semiconductor substrate 702.As would be understood by one of ordinary skill in the art, in variousembodiments the substrate may be a silicon substrate, a compoundsemiconductor substrate, a diamond substrate, a quartz glass substrate,or a polymer substrate, among others. The substrate is formed to includea substantially flat region. The flat region may be leveled and smoothed704 by known processes including, for example, mechanical polishing,etching, and chemical mechanical processing. In a further processingstep 706 a convex or concave region is formed on the substrate. Thisconvex or concave region may be formed by deposition or removal ofmaterial.

A plurality of photosensors are formed 708 on an upper surface of theconvex or concave region. In one embodiment of the invention, one ormore analog to digital converter circuits are formed on the flat regionof the substrate 710. A signal processor circuit may also be formed onthe flat region of the substrate 712 according to one aspect of theinvention, and in another aspect of the invention, a random accessmemory device may be formed 714 on the flat region of the substrate. Theanalog to digital converter circuits, the signal processor circuit andthe memory device may be formed according to conventional methods,including masking, etching, mask removal, and deposition, as would beunderstood by one of skill in the art.

In like fashion, conventional plating and sputtering methods may beemployed, along with masking and etching, to form interconnectcircuitry. The interconnect circuitry may be of metallic, or otherwiseconductive materials, and may be used to couple the photosensor is tothe analog to digital converter 716, to couple the analog to digitalconverter to the digital signal processor 718, and to couple the signalprocessor to the random access memory device 720.

After forming and interconnecting the various devices as describedabove, the manufacturing process may include testing of thephotodetector device 722, including calibration testing, temperaturestress testing, illumination stress testing, and other testing as wouldbe understood by one of skill in the art. In the course of devicetesting, calibration data may be acquired 724. This calibration data maybe stored in the random access memory 726, or otherwise used to modifythe performance of one or more of the photosensor devices. Accordingly,process variation exhibited by the various photosensor devices may becompensated for by executing calibration and trimming steps during orafter manufacturing of the array. Other corrective actions, as known inthe art, including the provision and substitution of redundantphotosensors in an array during manufacturing, would be readily appliedto the subject photosensor arrays.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Accordingly, theinvention is not to be considered as limited by the foregoingdescription, but is only limited by the scope of the claims appendedhereto.

1. (canceled)
 2. A method of forming an image signal comprising:receiving a flux of photons at a convex photodetector, said convexphotodetector including a plurality of photosensors, said plurality ofphotosensors each having a different orientation with respect to apropagation vector of said flux of photons; generating a plurality ofintensity signals at said plurality of photosensors respectively, eachof said intensity signals being related to said respective orientation;receiving said plurality of intensity signals at a signal processordevice; and computing, with said signal processor device, an imagesignal related to said plurality of intensity signals.
 3. A method offorming an image signal as defined in claim 2 wherein said convexphotodetector comprises a substantially hemispherical photodetector. 4.A method of forming an image signal as defined in claim 2 wherein saidconvex photodetector comprises a substantially ellipsoidalphotodetector.
 5. A method of forming an image signal as defined inclaim 2 wherein computing said image signal comprises: determining anintensity and angular position, with respect to said convexphotodetector, of at least one source of said flux of photons.
 6. Amethod of forming an image signal as defined in claim 2 wherein saidreceiving a flux of photons comprises: receiving substantiallycollimated light waves from a light source outwardly of said convexphotodetector.
 7. A method of forming an image signal as defined inclaim 2 wherein said plurality of photosensors comprises a plurality ofCMOS photosensors.
 8. A method of forming an image signal as defined inclaim 2 wherein said plurality of photosensors comprises a plurality ofcharge coupled devices.
 9. A method of forming an image signal asdefined in claim 2 wherein each of said plurality of photosensorsincludes a substantially planar light-receiving surface.
 10. A method offorming an image signal as defined in claim 2 wherein said signalprocessor device comprises a computer processor disposed on a commonsubstrate with said convex photodetector.
 11. A method of forming animage signal as defined in claim 10 wherein said signal processor devicecomprises a digital electronic computer.
 12. A method of forming animage signal as defined in claim 2 wherein said signal processor deviceincludes a computer readable memory, said computer readable memory beingadapted to contain a program, said program being adapted to transformsaid plurality of intensity signals by matrix inversion to produce saidimage signal.
 13. A method of forming an image signal as defined inclaim 2 wherein said plurality of intensity signals includes a pluralityof analog electronic signals, said method further comprising: receivingsaid plurality of analog electronic signals at least one analog todigital converter; and producing a plurality of digital electronicsignals. 14.-22. (canceled)
 23. A method of converting a photon flux toa focused image comprising: receiving a photon flux of a finiteintensity at a plurality of photosensors, said flux of photonspropagating along an axis of propagation, said plurality of photosensorseach having a different angular orientation with respect to said axis ofpropagation; generating a plurality of intensity signals at saidplurality of photosensors respectively, each of said plurality ofintensity signals related to said finite intensity and said angularorientation; receiving said plurality of intensity signals at a signalprocessor; generating an image signal with said signal processor basedon said plurality of intensity signals; and displaying a focused imagebased on said image signal. 24.-29. (canceled)
 30. A photodetectorcomprising: a substrate; a convex support member disposed on saidsubstrate, said convex support member having an upper surface; and aplurality of photosensors disposed on said upper surface.
 31. Aphotodetector as defined in claim 30 further comprising: a plurality ofanalog to digital converters disposed on said substrate, said pluralityof analog to digital converters being coupled to said plurality ofphotosensors respectively.
 32. A photodetector as defined in claim 31further comprising: a numerical signal processor including a digitalmemory device, said numerical signal processor being disposed on saidsubstrate, said numerical signal processor being coupled to saidplurality of analog to digital converters.
 33. A photodetector asdefined in claim 30, wherein said upper surface includes a substantiallysmooth hemispherical surface.
 34. A photodetector as defined in claim30, wherein said upper surface includes a substantially smoothellipsoidal surface.
 35. A photodetector as defined in claim 30, whereinsaid upper surface includes a substantially smooth ovoid surface.
 36. Aphotodetector as defined in claim 30, wherein said upper surfaceincludes a plurality of substantially flat terraces.
 37. A photodetectoras defined in claim 30, wherein said substrate comprises a siliconsubstrate.
 38. A photodetector as defined in claim 30, wherein saidsubstrate comprises a compound semiconductor substrate. 39-54.(canceled)